research report 095hse health & safety executive accident statistics for floating offshore units on...

HSE Health & Safety

Executive

Accident statistics for floating offshore units on the UK Continental Shelf

1980 - 2001

Prepared by Det Norske Veritas Industry AS

for the Health and Safety Executive 2003

RESEARCH REPORT 095

HSE Health & Safety

Executive

Accident statistics for floating offshore units on the UK Continental Shelf

1980 - 2001

Espen Funnemark Det Norske Veritas Industry AS

Safety & Process Advisory Services Veritasveien 1

1322 Hovik Norway

Eoin Young HSE Offshore Division

Room G SW Rose Court

London SE1 9HS

This project updates previous project; Accident Statistics for Mobile Offshore Units on the UK Continental Shelf, 1980 - 1998. The Health and Safety Executive (HSE) published the project as OTO 2000/091. This project follows the same format for floating offshore units and extends the data coverage to 21 years, 1980 - 2001.

The work was commisioned by the HSE as it had been noted that event frequencies quoted in the safety cases of offshore installations tended to be lower than experience would anticipate.

It has been noted that extensive use has been made of OTO 2000/091 in safety cases submitted following publication. Typically a review of relevant incidents has assisted the duty holder in confirming that he has in place adequate mitigating measures.

This report and the work it describes were funded by the HSE. Its contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.

HSE BOOKS

© Crown copyright 2003

First published 2003

ISBN 0 7176 2210 X

All rights reserved. No part of this publication may be

reproduced, stored in a retrieval system, or transmitted in

any form or by any means (electronic, mechanical,

photocopying, recording or otherwise) without the prior

written permission of the copyright owner.

Applications for reproduction should be made in writing to:

Licensing Division, Her Majesty's Stationery Office,

St Clements House, 2-16 Colegate, Norwich NR3 1BQ

or by e-mail to [email protected]

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Table of Contents Page

1 EXECUTIVE SUMMARY ......................................................................................... 1

1.1 Introduction and background 1

1.2 Confidentiality 1

1.3 Objectives, results and conclusions 1

2 INTRODUCTION ....................................................................................................... 5

3 OBJECTIVES AND SCOPE OF WORK.................................................................... 7

4 EXPOSURE DATA..................................................................................................... 9

4.1 Mobile offshore drilling units (MODUs) 9

4.2 Mobile Production Units (MOPUs) 10

4.3 Monohull units 12

4.4 Accommodation Units 14

5 INCIDENT REPORTING IN UK WATERS............................................................ 15

6 ORION DATABASE................................................................................................. 17

6.1 Available data 17

6.1.1 Incident category codes 18

6.1.2 Operation codes 19

6.1.3 Dangerous occurrence type codes 19

6.1.4 Broad Incident Type codes 20

6.2 Event classification and coding principles 21

6.3 Result of interrogation 22

6.3.1 All floating units 24 6.3.2 Mobile Drilling Units (MODUs) 26 6.3.3 Mobile Production Units (MOPUs) 38 6.3.4 Monohull Units 46 6.3.4.1 FPSOs 47 6.3.4.2 FSUs 52

Accommodation Units 566.3.5

7 FOCUS/SHIELD DATABASE ................................................................................. 61


8 THE MAIB DATABASE .......................................................................................... 63

8.1 Available data and reporting 63


9 WOAD ....................................................................................................................... 67

9.1 Available data 67

9.2 Result of interrogation 68 9.2.1 All floating units 70 9.2.2 Mobile Drilling Units (MODUs) 71

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9.2.2.1 Drilling jackups and semisubmersibles 71 9.2.2.2 Drill ships 78 9.2.3 Mobile Production Units (MOPUs) 79 9.2.3.1 Production semisubmersibles 79 9.2.3.2 Production jackups 80 9.2.3.3 Tension-leg platforms 80 9.2.4 Monohull Units 80 9.2.4.1 FPSOs 80 9.2.4.2 FSUs 80 9.2.5 Accommodation Units 81

10 BLOWOUT DATABASE ......................................................................................... 83

11 ACCIDENT STATISTICS ........................................................................................ 85

11.1 Accident frequencies, All databases combined 85

11.2 Occurrence frequencies, All databases combined 87 11.2.1 Mobile Drilling Units (MODUs) 88 11.2.2 Mobile Production Units (MOPUs) 100 11.2.3 Monohull Units 108 11.2.3.1 FPSOs 109 11.2.3.2 FSUs 114 11.2.4 Accommodation Units 118

11.3 Frequencies, floating units on NCS 122

11.4 Frequencies, fixed units on NCS 122

12 CONCLUSIONS...................................................................................................... 123

13 REFERENCES ........................................................................................................ 125

Appendix A HSE Sun Safety System; Dangerous Occurrence Type Codes

This report is part 1 of the published data.

Part 2 is the associated spreadsheet listing

individually the coding and text for each incident.

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1 EXECUTIVE SUMMARY

1.1 Introduction and background In a recent project, four databases holding information about UK Continental Shelf (UKCS) semi-submersible flooding incidents were interrogated. The survey revealed that that none of them had a complete recording of such incidents. In addition, it was identified that there were incidents which were not recorded in any of these sources. Consequently, the event frequencies being obtained varied with the availability of sources. Obviously, there was no reason to believe that the situation and figures for other types of events on floating units should be any different. Hence, it was proposed to initiate a similar type of project, but addressing all types of risks to floating units.

Prior to 1991 the regulation of offshore safety was the role of the Department of Energy, DEn. During the period that the DEn was in place, data concerning incidents and accidents on offshore installations within the UKCS was passed to the WOAD databank. From 1991 the role of regulation of offshore safety passed to the HSE and very little, if any, data was passed to WOAD. The Health And Safety At Work Act, HASAWA, Section 28, Disclosure of Information, being interpreted at the time by the HSE so as to prevent the transfer of such information. As a consequence, from 1991 until very recently no UKCS offshore installation incident data has been made available to WOAD by the HSE. Therefore current WOAD risk estimates exclude incidents and accidents on the UKCS except for those where adequate quality information has been made available in the public domain.

A recent HSE legislative review of Section 28 allows, conditionally, the transfer of such data from the HSE to WOAD. Provided that the project is in line with the general function of the HSE "To secure the health, safety and welfare of persons at work" then it will not be in contravention of HASAWA. This project has been accepted by the Open Government Unit of the HSE as fulfilling that condition and in addition confidentiality is protected in that the information so transferred has been "ring fenced".

1.2 Confidentiality In order to ensure that the final results of the project were accurate and in line with the Quality Control requirements of the WOAD databank it was necessary to obtain "raw" data from each of the Databases interrogated. Raw data being defined as the data concerning a specific incident which identified the installation, operator, location, date and time. The data so obtained enabled quality checks to be undertaken on the different databases to prevent double counting of an incident or accident.

It is a condition of the contract between the HSE and DNV, the custodians of the WOAD databank, that any information so obtained will only be exported in a non attributable form to protect confidentiality. That is, any request for data obtained by WOAD as a result of this project will result in data being supplied which is non attributable and will not allow identification of the name of the installation, company, location, date or time of an incident. It will thus be impossible to pinpoint the installation or operator by any means.

1.3 Objectives, results and conclusions The main objective of the project is to obtain complete statistics (i.e. accident frequencies) for accidents and incidents having occurred on floating units engaged in the oil and gas activities on the UKCS in the period 1980-2001. Floating units in this project are defined as comprising semi

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submersibles, jackups, ships and tension-leg platforms engaged in drilling, accommodation, production and storage.

The results from this study would serve as a reference document for data to be used in future Risk Assessments of offshore floating units and furthermore, be a valuable reference document for UK Health & Safety Executive (HSE)/ Offshore Safety Division (OSD) when reviewing Safety Cases.

To fulfil this objective, relevant databases were interrogated with respect to both population and accident data. This forms a complete data basis for obtaining comprehensive accident statistics for the said type of units, geographical area and time period. The following databases were selected for interrogation:

• FOCUS, UK HSE - Field Operations Division • ORION (the former Sun Safety System), UK HSE-Offshore Safety Division • MAIB accident database, UK Marine Accidents Investigation Bureau • Offshore Blowout Database, SINTEF, Norway • Worldwide Offshore Accident Databank WOAD, Det Norske Veritas (DNV), Norway

By combining and merging the results from the interrogation of the three databases, ORION, MAIB and WOAD, the accident frequencies for floating units in the UKCS in the period 19802001 are estimated. The other two databases did not contain information about accidents beyond that which was already reported. In the two following tables the accident frequencies (i.e. number of accidents per unit year) are given per type of installation, period and data source. N denotes number of accidents and F denotes frequency, i.e. number of accidents per unit and year. The source All databases combined refers to the database obtained by pooling the databases WOAD, ORION and MAIB and removing the overlapping records. The data are presented for WOAD and ORION separately due to the amount of data in these databases. The information contained in MAIB does not contribute significantly to the results.

The result after having interrogated the databases and removing overlapping records is shown in an Excel spreadsheet, which may be downloaded from HSE’s Internet Home Page www.hse.gov.uk , documenting a total of 3112 events comprising accidents, hazardous situations and near-misses. Note: Best efforts have been made to ensure complete anonymity within the free text associated with each incident. However, it is possible that within the 3112 incidents some anonymisation has been missed.

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Table 1 Mobile drilling units (MODUs) and mobile production units (MOPUs). Accident frequencies (per unit year). UKCS, 1980-2001.

MODUs MOPUs

Source-> Period

WOAD ORION All databases combined


1980-89 0.087 0.991 1.053 0.300 2.519 2.690

1990-99 0.106 2.353 2.442 0.084 1.955 1.989

1980-2001 0.097 1.791 1.864 0.120 2.528 2.588

Table 2 Monohulls and all floating units. Accidents frequencies (per unit year). UKCS, 1980-2001.

Monohulls All floatings

Source-> Period



1980-89 - 0.414 0.414 0.094 1.043 1.108

1990-98 0.139 2.465 2.588 0.107 2.331 2.419

1980-2001 0.094 2.738 2.823 0.098 1.906 1.978

The main conclusions from the work undertaken in this project are summarised below.

• The event frequencies strongly vary with the source being used As identified in the recent project on semi-submersibles, this project also clearly shows that the event frequencies being obtained strongly depend on which database is being interrogated.

• The main source for accident and incident information being available for the UKCS offshore industry should be the HSE’s ORION

Due to the accident reporting requirements for floating units on the UK Continental Shelf (UKCS), the main source for accident and incident information being available for the UKCS offshore industry should be the HSE’s ORION. The interrogation of ORION in this project showed that the database contains information for accidents and incidents ranging from hazardous situations and working accidents with no consequences to severe damage and total loss of units.

• Large difference in number of accidents between WOAD and ORION When comparing the information held by DNV’s Worldwide Offshore Accident Databank (WOAD) and ORION, there is a big difference in number of accidents. This is mainly explained by the fact that WOAD receives information about accidents through publicly available sources, which in most cases only addresses events with large consequences. However, if considering the Norwegian Continental Shelf (NCS), WOAD contains information about accidents and incidents on the same level as ORION on the UKCS, due to an arrangement between the Norwegian Petroleum Directorate and DNV for transferring information to WOAD.

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• Increase in event frequencies when merging all databases together If all floating units are considered for the period 1990-2001, then this study demonstrates a total accident frequency of 2.8 per installation per year. This figure is a factor about 25 times higher than that which is obtained from the publicly available database, WOAD.

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2 INTRODUCTION In a recent project (ref. /1/), four databases holding information about UK Continental Shelf (UKCS) semi-submersible flooding incidents were interrogated. These were UK Health & Safety (HSE) - Field Operations Division’s (HSE-FOD) “FOCUS” database, HSE-OSD’s “Sun Safety System” database (from 2000: ORION), Marine Accidents Investigation Bureau’s (MAIB) accident database, and Det Norske Veritas’ (DNV) “Worldwide Offshore Accident Databank”, WOAD”. The survey revealed that that none of them had a complete recording of such incidents. In addition, it was identified that there were incidents that were not recorded in any of these sources. Consequently, the event frequencies being obtained varied with the availability of sources.

Obviously, there is no reason to believe that the situation and figures for other types of risks to floating units are any different compared to the one addressed in that project. Hence, it was proposed to initiate a similar type of project, but addressing all types of risks to floating units.

This report documents the results from this project.

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3 OBJECTIVES AND SCOPE OF WORK The main objective of the project is to obtain complete statistics (i.e. accident frequencies) for accidents and incidents having occurred on floating units engaged in the oil and gas activities on the UK Continental Shelf in the period 1980-2001. Floating units in this project are defined to comprise drilling, accommodation, and floating production and storage units. The classification of units is according to the following:

Category Type of unit

Mobile drilling unit (MODU) Jackup, Semisubmersible

Mobile production unit (MOPU) Jackup, Semisubmersible, Tension-leg platform (TLP)

Monohull Floating storage unit (FSU), Floating production, storage and offloading unit (FPSO)*

Accommodation unit Jackup, Semisubmersible

*): It could be argued that the FPSOs could have been classified as a MOPU.

It should be noted that in this project the FPSOs and TLPs are classified as ”mobiles” even though they are temporarily fixed during their production phase.

The results from this study would serve as a reference document for data to be used in future Risk Assessments of offshore floating units and furthermore, be a valuable reference document for HSE/OSD when reviewing Safety Cases.

To fulfil this objective, relevant databases were interrogated with respect to both population and accident data. This forms a complete data basis for obtaining comprehensive accident statistics for the said type of units, geographical area and time period. The following databases were selected for interrogation:

• FOCUS, UK HSE - Field Operations Division *• ORION , UK HSE-Offshore Safety Division

• MAIB accident database, UK Marine Accidents Investigation Bureau • Offshore Blowout Database, SINTEF, Norway • Worldwide Offshore Accident Databank WOAD, Det Norske Veritas (DNV), Norway *): The former “Sun Safety System”

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4 EXPOSURE DATA Exposure (population) data in this context relates to the number of unit- (or rig-) years for each type of platform or installation. By interrogating relevant sources holding such information, the number of unit-years are obtained for each year and type of unit for the UKCS in the period 1980-2001. The results are shown in several tables in the following sub-chapters. The classification of units is shown in the previous chapter.

4.1 Mobile offshore drilling units (MODUs) From WOAD, the exposure data for MODUs on the UKCS are obtained. The data are given in Table 3 below.

Table 3 MODUs. UKCS, 1980-2001. Number of unit years

Type of MODU

Year Jackup Semisub Drillship Total

1980-89 205.9 342.1 2.8 550.8

1990 27.8 46.1 0.4 74.3

1991 29.7 49.3 0.4 79.4

1992 29.0 48.2 0.4 77.6

1993 26.6 44.2 0.4 71.2

1994 21.7 36.0 0.3 58.0

1995 20.7 34.4 0.3 55.4

1996 23.0 38.2 0.3 61.5

1997 21.7 36.1 0.3 58.1

1998 22.0 36.5 0.3 58.8

1999 24.0 32.3 1.0 57.3

2000 22.4 30.2 0.3 52.9

2001 23.1 30.4 0.4 53.9

1990-99 246.2 401.3 4.1 651.6

1980-2001 497.6 804.0 7.6 1309.2

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4.2 Mobile Production Units (MOPUs) These units comprise conversions and purpose-built producing jackups, semi-submersibles, and tension-leg platforms (TLPs). From ref. /3/ the number of unit years are calculated. Table 4 summarises the results of this exercise.

Table 4 MOPUs. UKCS, 1980-2001. Number of unit years

Name of unit Type of unit Date of first oil production (mm-yy)

Date of abandonment

(mm-yy)

Number of unit-years 1980-2001

AH001 Semi-sub 07-89 12.5

Balmoral 16/21 Semi-sub 11-86 15.17

Buchan ‘A’ Semi-sub 05-81 20.67

Elgin TPG 5000 Jackup 01-98 4.0

Harding Jackup 04-96 5.75

Hutton TLP TLP 08-84 05-2001 16.84

Janice ‘A’ 2 Semi-sub 02-99 2.92

North Sea Pioneer Semi-sub 04-89 01-91 1.75

Northern Producer1 Semi-sub 08-92 9.42

Sedco 707 Semi-sub 05-94 02-99 4.75

Transworld 58 Semi-sub 06-75 12-84 4.92

All - - - 98.68

1): ex Emerald Producer; 2): ex West Royal

The exposure data are further broken down and distributed on year and type of unit. The table below summarises the results.

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Table 5 MOPUs. UKCS, 1980-2001.

Number of unit years per year and type of unit

Type of unit

Year Semi-sub Jackup TLP Total

1980-89 18.0 - 5.42 23.42

1990 4.0 - 1.0 5.0

1991 3.0 - 1.0 4.0

1992 3.42 - 1.0 4.42

1993 4.0 - 1.0 5.0

1994 4.67 - 1.0 5.67

1995 5.0 - 1.0 6.0

1996 5.0 0.75 1.0 6.75

1997 5.0 1.0 1.0 7.0

1998 5.0 2.0 1.0 8.0

1999 5.0 2.0 1.0 8.0

2000 5.0 2.0 1.0 8.0

2001 5.0 2.0 0.42 8.0

1990-99 44.09 5.75 10.0 59.84

1980-2001 72.09 9.75 16.84 98.68

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4.3 Monohull units These units comprise Floating Storage Units (FSUs) and Floating Production, Storage and Offloading units (FPSOs). Based on information from HSE-OSD’s database on UKCS monohulls, the number of unit years are calculated. Table 6 summarises the results from querying that database.

Table 6 Monohulls. UKCS, 1980-2001. Number of unit years

Name of unit Type of unit Constr. (P/C)*

Date of first oil production (mm

yy)

Date of abandonment

(mm-yy)

No. of unit-years 1980-2001

Ailsa Craig FSU C 08-92 02-96 3.50

Alba FSU FSU P 01-94 8.00

Anasuria FPSO P 10-96 5.25

Bleo Holm FPSO P 04-99 2.75

Captain FPSO FPSO P 06-97 4.58

Curlew FPSO FPSO C 11-97 4.17

Fulmar FSU FSU C 02-82 06-94 12.33

Glas Dowr FPSO P 08-97 06-99 1.92

Global Producer III FPSO P 01-2001 1.00

Gryphon ‘A’ FSPO P 01-93 9.00

Haewene Brimm ** FPSO P 02-99 2.92

Liverpool Bay Osi FSU P 03-96 5.83

Nordic Apollo FSU C 12-2000 1.08

North Sea Producer FPSO C 08-97 4.42

Petrojarl 1 FPSO P 03-95 04-2001 6.08

Petrojarl Foinaven FPSO P 11-97 4.17

Ramform Banff FPSO P 02-99 2.92

Schiehallion FPSO FPSO P 07-98 3.50

Seillean FPSO P 04-88 11-97 9.58

Triton FPSO P 08-99 2.42

Uisge Gorm FPSO C 08-95 6.42

Vinga FSU P 09-93 10-97 5.08

All 105.91

*) C: Converted tankers, P: Purpose-built **) Ex. Berge Hugin

The exposure data are further broken down and distributed on year and type of unit. The two following tables summarise the results.

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Table 7 Monohulls. UKCS, 1980-2001. Number of unit years per type of unit

Type of unit

Year FPSO FSU Total

1980-89 1.75 7.92 9.67

1990 1.0 1.0 2.0

1991 1.0 1.0 2.0

1992 1.0 1.42 2.42

1993 2.0 2.33 4.33

1994 2.0 3.42 5.42

1995 3.25 3.0 6.25

1996 4.25 2.92 7.17

1997 6.58 2.75 9.33

1998 9.5 2.0 11.5

1999 12.5 2.0 14.5

2000 13.0 2.08 15.08

2001 13.25 3.0 16.25

1990-99 43.08 21.83 64.91

1980-2001 71.08 34.83 105.91

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Table 8 Monohulls. UKCS, 1980-2001.

Number of unit years per type of unit and construction

Type of unit and construction

FPSO FSU

Year Purpose-built Converted Purpose-built Converted

1980-89 1.75 7.92

1990 1.0 1.0

1991 1.0 1.0

1992 1.0 1.42

1993 2.0 0.33 2.0

1994 2.0 2.0 1.42

1995 2.83 0.42 2.0 1.0

1996 3.25 1.0 2.83 0.08

1997 5.0 1.58 2.75

1998 6.5 3.0 2.0

1999 9.5 3.0 2.0

2000 10.0 3.0 2.0 0.08

2001 10.25 3.0 2.0 1.0

1990-99 34.08 9.0 13.91 7.92

1980-2001 56.08 15.0 17.91 16.92

4.4 Accommodation Units Several potential sources for such information were consulted with no success. It was concluded that if such data was to be obtained, extensive manual work had to be performed. Hence no exposure data for accommodation units was obtained within the scope of this study. This implies that no accident and incident frequencies for these units are calculated in this report.

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5 INCIDENT REPORTING IN UK WATERS The existing reporting requirements of incidents on floating units operating (working, in transit or docked) on the UKCS depend on geographical location and operation mode at the time of the incident. The receiver of information is either the Health and Safety Executive - Offshore Safety Division (HSE-OSD), the Health and Safety Executive – Field Operations Division (HSE-FOD) or the Marine Accident Investigation Branch (MAIB).

In the following three chapters one may find some documentation of the incident and accident reporting regime for offshore vessels in UK waters. This regime may be summarised as shown in below.

Table 9 Overview of the UKCS incident reporting regime; UK and non-UK flagged vessels

Location/activity Flag Report to

Within the 12-mile limit and not an Offshore Installation (e.g. in transit)

UK MAIB

Non UK* MAIB

Outside the 12-mile limit and not an Offshore Installation (e.g. in transit)

UK MAIB

Non UK* Flag state

Working as an Offshore Installation (e.g. drilling, production, accommodation)

UK HSE-OSD

Non UK* HSE-OSD

Alongside at a shipyard (e.g. for repair or maintenance)

UK HSE-FOD

Non UK* HSE-FOD

*): Presumably the non-UK flagged vessels would also report to the Flag State

Descriptions of the three main databases holding this information and operated by the HSE and

MAIB, are also given.

Further details regarding the reporting regime and the databases may be found in ref. /1/.

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6 ORION DATABASE The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR 95) arrangement came into force on 1 April 1996 and requires that all work-related accidents, diseases and dangerous occurrences are to be reported to the HSE. It applies to all work activities, but not to all types of incidents. The incidents are to be reported using the OIR/9B and F2508A forms. These forms are to be completed and submitted to the local HSE-OSD office.

Prior to 1 April 1996 injuries and dangerous occurrences were reported on the OIR/9A form. This form was created under the Mineral Workings (Offshore Installations) Act 1971 and the Offshore Installations (Inspectors and Casualties) Regulations 1973.

The information submitted on the OIR/9A, OIR/9B and F2508A forms are recorded in a database, “ORION” (the former Sun Safety System), run by the HSE-OSD offices in Bootle, Liverpool.

The Sun Safety System (now ORION) was primarily developed to record incident data reported on the OIR/9A form. Other information is however recorded on the database, including details of inspections, investigations, prosecutions and the registration and location details of Offshore Installations. The OIR/9A form was first published in October 1990, and the Sun Safety System was implemented in 1st January 1991. The Sun Safety System does however contain some data on pre 1991 incidents (imported from previous systems maintained by the Safety Directorate of the Department of Energy), though not all fields on the OIR/9A form are available for this data. The Sun Safety System was decommissioned year 2000 and all data from 1991(incl.) was transferred to ORION.

Note that notification of hydrocarbon releases (voluntarily submitted on the OIR/12 form) are also recorded in a separate and specifically designed database which is maintained by the HSE-OSD offices in Bootle, Liverpool.

6.1 Available data For the purposes of this project HSE-OSD made available information from ORION on Excel spreadsheets, one per year for the period 1980-2001. Incidents categorised as “slips-trips-and-falls” were excluded. Each relevant incident was reported with the following parameters:

• Date of incident • Time of incident • Incident category (coded, codes given in section 6.1.1) • Name of installation • Duty holder • Operation (coded, codes given in section 6.1.2) • Number of injuries • Dangerous occurrence type (coded, codes given in section 6.1.3) • Accident kind (coded, codes given in section 6.1.4) • Incident description (free text)

A sample record is given below (example of incident reported under RIDDOR 95).

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Date 05-Aug-97

Time 06:00

Category 4

Name < Rig name >

Operation 2

Dangerous 13 occurrence type

Broad incident type

Incident no. nnnnn

Description Drilling 12 1/4" hole at 2293m well flowing shut in well with BOP circulated with 2.10sg mud opened BOP’s - still flowing increased mud to 2.14sg well flowing slightly ran packer flowed brine via DP depleted kick zone to 1.71sg well dead with 2.12sg mud reduced mud to 1.90sg well stabilised set cement plug squeezed cmt well flowing stabilised well with 2.0sg set second cement plug reduced mud weight to 1.95sg drilled cement - well flowing stabilised well with 2.0sg change-out to 2.0sg WBM.

It is a condition of the contract between the HSE and DNV that any information so obtained will only be exported in a non attributable form to protect confidentiality. That is, data exported to any type of database should not allow identification of the name of the installation, company, location, date or time of an incident. It will thus be impossible to pinpoint the installation or operator by any means.

The introduction of RIDDOR 95 offshore from 1/4/96 brought with it the use of Dangerous Occurrence (DO) type codes for the first time - DOs were recorded prior to this, but not against any specific coding and under different legislation (e.g. Mineral Workings (Offshore Installations) Act 1971).

The recording of Broad Incident Type (BIT) is held against earlier data and prior to RIDDOR 95 was actually recorded on the report form by the duty holder although post RIDDOR, it has been OSD who have coded BIT.

6.1.1 Incident category codes The following codes are used for the parameter Incident category.

Code Description

1 Fatality

2 Major Injury

3 Over 3 day Injury

4 Dangerous Occurrence (DO)

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6.1.2 Operation codes The following codes are used for the parameter Operation.

Code Description

1 Production

2 Drilling / workover

3 Maintenance

4 Diving

5 Construction / commissioning

6 Deck operations

7 Domestic / catering

8 Modification of plant / structures

9 Transport

10 Other

6.1.3 Dangerous occurrence type codes A complete list of the codes used for the parameter Dangerous occurrence type is found in Appendix A. This field is only completed for category 4 incidents (“Dangerous Occurrences”) and only for incidents in the period from April 1996 to date (ref. RIDDOR 95).

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1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

6.1.4 Broad Incident Type codes The following codes are used for the parameter Broad Incident Type (BIT). This field is only completed for category 1-3 incidents (Fatalities and Injuries) and only for incidents in the period from April 1996 to date (ref. RIDDOR 95). This field is also referred to as Broad Incident Type.

Code Description

Loss of containment

Fire / explosion

Air transport

Sea transport

Slips / trips / falls

Falling objects

Handling goods / materials

Lifting / crane operations

Use of hand tools

Use of machinery

Exposure to harmful substances

Diving related

Electrical

Structural / foundation

Mooring

Radiation

Other

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6.2 Event classification and coding principles The WOAD concept of classifying events has been selected for the review work on the records received from HSE’s ORION. Hence the events are categorised according to the table below.

Table 10 Event classification, WOAD

Type of event Explanation

Anchor failure Problems with anchor/anchor lines, mooring devices, winching equipment or fairleads (e.g. anchor dragging, breaking of mooring lines, loss of anchor(s), winch failures).

Blowout An uncontrolled flow of gas, oil or other fluids from the reservoir, i.e. loss of 1. barrier (i.e. hydrostatic head) or leak and loss of 2. barrier, i.e. BOP/DHSV.

Capsize Loss of stability resulting in overturn of unit, capsizing, or toppling of unit.

Collision Accidental contact between offshore unit and/or passing marine vessel when at least one of them is propelled or is under tow. Examples: tanker, cargo ship, fishing vessel. Also included are collisions with bridges, quays, etc., and vessels engaged in the oil and gas activity on other platforms than the platform affected, and between two offshore installations (to be coded as CN only when intended for close location).

Contact Collisions/accidental contacts between vessels engaged in the oil and gas activity on the platform affected, e.g. support/supply/stand-by vessels, tugs or helicopters, and offshore installations (floating or fixed). Also are included collisions between two offshore installations only when these are intended for close location.

Crane Any event caused by or involving cranes, derrick and drawworks, or any other lifting equipment.

Explosion Explosion

Falling object Falling load/dropped objects from crane, drill derrick, or any other lifting equipment or platform. Crane fall and lifeboats accidentally to sea and man overboard are also included.

Fire Fire.

Foundering Loss of buoyancy or unit sinking.

Grounding Floating installation in contact with the sea bottom.

Helicopter Accident with helicopter either on helideck or in contact with the installation.

Leakage Leakage of water into the unit or filling of shaft or other compartments causing potential loss of buoyancy or stability

21

Type of event Explanation

problems.

List Uncontrolled inclination of unit.

Machinery failure Propulsion or thruster machinery failure (incl. control)

Off position Unit unintentionally out of its expected position or drifting out of control.

Spill/release “Loss of containment”. Release of fluid or gas to the surroundings from unit's own equipment/vessels/tanks causing (potential) pollution and/or risk of explosion and/or fire.

Structural Breakage or fatigue failures (mostly failures caused by weather, but not necessarily) of structural support and direct structural failures. "Punch through" also included.

Towing/towline Towline failure or breakage

Well problem Accidental problem with the well, i.e. loss of one barrier (hydrostatic head) or other downhole problems.

Other Event other than specified above

The categorisation of the incidents has been performed according to principles outlined below.

• Events coded as Falling load involve loads and objects either rolling, leaning, tilting, falling, rotating, swinging, or sliding. Man over board is also included here.

• “Occupational Hazard” (OH) incidents, with personal injuries or not, are defined to be events which are not related to operations of equipment and events caused by obvious human errors during maintenance. Such events have only been counted, but are excluded from the statistics (i.e. no frequencies).

• Anchor handling involving supply boat which causes personal injuries to personnel being involved are coded as Anchor failure (and not OH).

• Maloperation of lifting equipment or technical failure leading to falling load is coded as Crane failure + Falling load.

• Problems with riser tensioners are coded as Crane failure • Events involving equipment or part of equipment bursting or blowing out, are coded as

Spill/Release • Events involving problems with gangways/bridges between floating unit and other floating or

fixed units, are coded as Out of position + Falling load. • Incidents that occur during maintenance indicates lack of design have been coded

accordingly (crane failure, falling load, anchor failure, etc.)

6.3 Result of interrogation The information that was available for each incident has been reviewed and the chain of events being obtained. The classification of events has been done according to the WOAD concept (see previous section). One accident may comprise a chain of consecutive events (accident outcomes or occurrences), e.g. a blowout resulting in explosion, fire and oil spill. This means that one single accident or incident may give rise to several occurrences. The total number of occurrences will thus be much higher than the total number of accidents recorded. When giving accident

22

frequencies per type of event, this is presented as number of occurrences per unit per year (ref. sections 6.3.2-6.3.4).

However, when presenting frequencies irrespective of type of event, the figures are given as number of accidents per unit per year (ref. section 6.3.1).

The two following tables summarise the result of the interrogation of data available from ORION, i.e. the number of incidents per year. The available data material comprises a total of 2991 accidents.

It should be noted that in addition to the identified “platform related events” a total of 745 “occupational hazard” are reported.

Table 11 Floating units. UKCS, 1980-2001. No. of accidents. Source: ORION

Number of accidents

Mobile Mobile Accommo- Monohull Units Total Drilling Units Production dation

Year of event Units Units

1980-89 546 59 28 4 637

1990 168 15 10 2 195

1991 240 17 10 4 271

1992 150 12 13 4 179

1993 110 9 16 12 147

1994 83 9 9 23 124

1995 109 15 7 21 152

1996 143 9 5 7 164

1997 198 12 4 14 228

1998 183 4 1 14 202

1999 149 15 59 223

2000 137 41 76 254

2001 129 35 1 50 215

1990-99 1533 117 75 160 1885

1980-2001 2345 252 104 290 2991

23

Table 12 Floating units. UKCS, 1980-2001. No. of occurrences. Source: ORION

Number of occurrences


Type of event Units Units

Anchor failure 183 25 9 217

Blowout 15 15

Capsize 1 6 7

Collision 8 91 99

Contact 160 4 8 8 180

Crane 1092 102 30 47 1271

Explosion 18 30 1 2 51

Falling object 1293 45 58 1396

Fire 142 10 29 181

Foundering 1 1 2

Grounding 1 1

Helicopter 6 3 1 10

Leakage 21 1 22

List 12 1 13

Machinery 2 100 1 103

Off position 17 1 10 2 30

Spill/release 226 1 158 385

Structural 52 6 7 6 71

Towing/towline 14 5 1 20

Well problem 201 1 1 203

Other 33 4 1 19 57

The results from performing a statistical analysis of the data are shown in the following sections. The exposure data used in the analysis are documented in chapter 4 of this report.

6.3.1 All floating units The table below shows the accident frequencies (i.e. number of accidents per unit-year) for all floating units on the UKCS in 1980-2001, except for the accommodation units for which no exposure data is obtained.

24

Table 13 Floating units. UKCS, 1980-2001.

Accident frequencies (per unit year). Source: ORION

Year of event

Mobile Drilling Units

Mobile Production

Units

Monohull Units Total*

1980-89 0.991 2.519 0.414 1.043

1990 2.261 3.000 1.000 2.276

1991 3.023 4.250 2.000 3.056

1992 1.933 2.717 1.655 1.966

1993 1.545 1.800 2.769 1.627

1994 1.431 1.588 4.246 1.664

1995 1.968 2.500 3.360 2.143

1996 2.325 1.333 0.977 2.129

1997 3.408 1.714 1.500 3.050

1998 3.112 0.500 1.217 2.634

1999 2.600 1.875 4.069 2.794

2000 2.590 5.125 5.040 3.343

2001 2.393 4.375 3.077 2.738

1990-99 2.353 1.955 2.465 2.331

1980-2001 1.791 2.528 2.738 1.906

*) Excl. accommodation units

25

6.3.2 Mobile Drilling Units (MODUs) In the following tables the number of occurrences and corresponding frequencies for mobile drilling units are given per type of platform and year/period. N denotes number of occurrences and F denotes frequency, i.e. number of occurrences per unit and year. Blank cells denote no occurrences recorded.

Table 14 Drilling jackups. UKCS, 1980-92.

No. of occurrences and occurrence frequencies (per unit year). Source: ORION

Period Year

1980-89 1990 1991 1992

Type of event N F N F N F N F

Anchor failure 3 0.015 1 0.034 1 0.034

Blowout 1 0.034

Capsize 1 4.9•10-3

Collision 1 4.9•10-3 1 0.034

Contact 23 0.112 6 0.216 6 0.202 8 0.276

Crane 95 0.461 26 0.935 32 1.077 14 0.483

Explosion 3 0.015

Falling object 83 0.403 22 0.791 33 1.111 13 0.448

Fire 14 0.068 4 0.144 5 0.172

Foundering 1 4.9•10-3

Grounding 1 4.9•10-3

Helicopter 1 4.9•10-3

Leakage 1 4.9•10-3 1 0.034

List 2 9.7•10-3 1 0.034 1 0.034

Machinery

Off position 1 0.036

Spill/release 18 0.087 7 0.252 2 0.067 14 0.483

Structural 11 0.053 1 0.036 1 0.034 2 0.069

Towing/towline 2 9.7•10-3 3 0.108 1 0.034

Well problem 13 0.063 2 0.072 2 0.067 2 0.069

Other 1 4.9•10-3 1 0.034 1 0.034

26



Year

1993 1994 1995 1996


Anchor failure 1 0.046

Blowout 1 0.046

Capsize

Collision

Contact 3 0.113 5 0.230 2 0.097

Crane 12 0.451 18 0.829 12 0.580 15 0.652

Explosion 1 0.046 1 0.048

Falling object 19 0.714 19 0.876 20 0.966 22 0.957

Fire 3 0.113 7 0.322 6 0.290 4 0.174

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release 8 0.301 10 0.461 6 0.290 2 0.087

Structural 1 0.038 1 0.048 1 0.043

Towing/towline

Well problem 2 0.092 4 0.193 6 0.261

Other 2 0.097

27



Year

1997 1998 1999

Type of event N F N F N F


Blowout 1 0.046 1 0.045

Capsize

Collision

Contact 2 0.092 5 0.227 3 0.125

Crane 27 1.244 31 1.409 9 0.375

Explosion

Falling object 31 1.429 45 2.045 15 0.625

Fire 5 0.230 3 0.136 4 0.167

Foundering

Grounding

Helicopter

Leakage 1 0.046

List

Machinery

Off position

Spill/release 3 0.138 6 0.273 9 0.375

Structural 1 0.045

Towing/towline

Well problem 14 0.645 30 1.364 8 0.333

Other 2 0.092 1 0.045

28

Table 17 Drilling jackups. UKCS, 2000-2001, 1990-99. 1980-2001.


Year Period

2000 2001 1990-99 1980-2001


Anchor failure 1 0.045 4 0.016 8 0.016

Blowout 4 0.016 4 8.0•10-3

Capsize 1 2.0•10-3

Collision 1 4.1•10-3 2 4.0•10-3

Contact 1 0.043 40 0.162 64 0.129

Crane 6 0.268 17 0.736 196 0.796 314 0.631

Explosion 2 8.1•10-3 5 0.010

Falling object 15 0.670 22 0.952 239 0.971 359 0.721

Fire 1 0.045 3 0.130 43 0.175 59 0.119




Leakage 2 8.1•10-3 3 6.0•10-3

List 2 8.1•10-3 4 8.0•10-3

Machinery 0

Off position 1 4.1•10-3 1 2.0•10-3

Spill/release 6 0.268 5 0.216 67 0.272 96 0.193

Structural 1 0.043 8 0.032 20 0.040

Towing/towline 4 0.016 6 0.012

Well problem 14 0.625 11 0.476 70 0.284 108 0.217

Other 7 0.028 8 0.016

29

Table 18 Drilling semisubmersibles. UKCS, 1980-92.


Period Year

1980-89 1990 1991 1992


Anchor failure 47 0.137 19 0.412 21 0.426 7 0.145

Blowout 1 0.022 2 0.041 1 0.021

Capsize

Collision 1 0.022

Contact 36 0.105 9 0.195 9 0.183 10 0.207

Crane 154 0.45 50 1.085 105 2.13 52 1.079

Explosion 7 0.02 2 0.043 2 0.041 1 0.021

Falling object 177 0.517 53 1.150 103 2.089 58 1.203

Fire 21 0.061 3 0.065 11 0.223 6 0.124

Foundering

Grounding


Leakage 6 0.018 3 0.065 4 0.081 1 0.021

List 1 2.9•10-3 1 0.022 3 0.061 1 0.021

Machinery

Off position 3 8.8•10-3 1 0.022 3 0.061 2 0.041

Spill/release 25 0.073 8 0.174 14 0.284 9 0.187

Structural 12 0.035 3 0.065 4 0.081 1 0.021

Towing/towline 3 8.8•10-3 1 0.022 2 0.041

Well problem 12 0.035 2 0.043 6 0.122 6 0.124

Other 3 8.8•10-3 4 0.087 6 0.122

30



Year

1993 1994 1995 1996


Anchor failure 17 0.385 5 0.139 5 0.145 16 0.419

Blowout

Capsize

Collision 1 0.026

Contact 7 0.158 3 0.083 2 0.058 3 0.079

Crane 15 0.339 12 0.333 43 1.25 45 1.178

Explosion 1 0.029

Falling object 29 0.656 18 0.500 51 1.483 54 1.414

Fire 5 0.113 3 0.083 7 0.203 4 0.105

Foundering

Grounding

Helicopter 1 0.028 2 0.058

Leakage 1 0.023 1 0.029

List

Machinery

Off position 3 0.068 1 0.028

Spill/release 5 0.113 8 0.222 5 0.145 10 0.262

Structural 1 0.023 1 0.029

Towing/towline

Well problem 5 0.113 1 0.028 1 0.029 10 0.262

Other 3 0.068 2 0.056

31



Year

1997 1998 1999


Anchor failure 17 0.471 8 0.219 4 0.124

Blowout 5 0.139

Capsize

Collision 1 0.027 2 0.062

Contact 3 0.083 4 0.110 5 0.155

Crane 75 2.078 52 1.425 29 0.898

Explosion

Falling object 92 2.548 63 1.726 65 2.012

Fire 4 0.111 2 0.055 7 0.217

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position 1 0.028 1 0.027

Spill/release 13 0.36 6 0.164 9 0.279

Structural 5 0.139 3 0.082 1 0.031

Towing/towline 1 0.028

Well problem 11 0.305 12 0.329 7 0.217

Other 2 0.055 3 0.093

32

Table 21 Drilling semisubmersibles. UKCS, 2000-2001, 1980-2001.


Year Period

2000 2001 1990-99 1980-2001


Anchor failure 2 0.066 2 0.066 119 0.297 170 0.211

Blowout 1 0.033 1 0.033 9 0.022 11 0.014

Capsize

Collision 1 0.033 5 0.012 6 7.5•10-3

Contact 2 0.066 2 0.066 55 0.137 95 0.118

Crane 64 2.119 61 2.007 478 1.191 757 0.942

Explosion 6 0.015 13 0.016

Falling object 78 2.583 69 2.270 586 1.460 910 1.132

Fire 6 0.199 2 0.066 52 0.130 81 0.101

Foundering

Grounding

Helicopter 3 7.5•10-3 5 6.2•10-3

Leakage 1 0.033 10 0.025 17 0.021

List 2 0.066 5 0.012 8 0.010

Machinery 2 0.066 2 2.5•10-3

Off position 13 0.032 16 0.020

Spill/release 10 0.331 6 0.197 87 0.217 128 0.159

Structural 1 0.033 19 0.047 32 0.040

Towing/towline 1 0.033 4 0.010 8 0.010

Well problem 11 0.364 7 0.230 61 0.152 91 0.113

Other 1 0.033 20 0.050 24 0.030

33

Table 22 Drillships. UKCS, 1980-92.


Period Year

1980-89 1990 1991 1992


Anchor failure 1 0.357 3 7.5 1 2.5

Blowout

Capsize

Collision

Contact 1 2.5

Crane 2 0.714 2 5.0 4 10

Explosion

Falling object 3 1.071 2 5.0 5 12.5

Fire 1 2.5

Foundering

Grounding

Helicopter

Leakage 1 2.5

List

Machinery


Spill/release 1 0.357

Structural

Towing/towline

Well problem

Other

34



Year

1993 1994 1995 1996


Anchor failure

Blowout

Capsize

Collision

Contact

Crane 1 2.5 2 6.667 1 3.333 4 13.333

Explosion

Falling object 2 5 2 6.667 5 16.667

Fire 1 3.333

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release

Structural

Towing/towline

Well problem

Other

35



Year

1997 1998 1999


Anchor failure

Blowout

Capsize

Collision

Contact

Crane 3 10

Explosion

Falling object 3 10

Fire

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position


Structural

Towing/towline

Well problem

Other

36

Table 25 Drillships. UKCS, 2000-2001, 1990-99, 1980-2001.


Year Period

2000 2001 1990-99 1980-2001


Anchor failure 4 0.976 4 0.526

Blowout

Capsize

Collision

Contact 1 0.244 1 0.132

Crane 2 5.000 17 4.146 19 2.500

Explosion

Falling object 2 5.000 19 4.634 21 2.763

Fire 2 0.488 2 0.263

Foundering

Grounding

Helicopter

Leakage 1 0.244 1 0.132

List

Machinery

Off position

Spill/release 1 0.244 1 0.132

Structural

Towing/towline

Well problem 2 5.000 2 0.263

Other 1 2.500 1 0.132

37

6.3.3 Mobile Production Units (MOPUs) In the following tables the number of occurrences and corresponding frequencies for mobile production units (MOPUs) are given per type of unit and year/period. The MOPUs comprise jackups, semi-submersibles and tension-leg platforms. N denotes number of occurrences and F denotes frequency, i.e. number of occurrences per unit and year. Blank cells denote no occurrences recorded.

Note that no occurrences have been recorded on production jackups prior to year 2000.

Table 26 Production jackups. UKCS. 1980-2001. No. of occurrences per unit year. Source: ORION

Year Type of event N F

2000 Crane 5 2.500

2000 Falling object 6 3.000

2000 Spill/release 2 1.000

2000 Well problem 2 1.000

2001 Crane 1 0.500

2001 Falling object 3 1.500

2001 Fire 1 0.500

2001 Spill/release 7 3.500

2001 Well problem 1 0.500

Average 19802001

Crane 6 0.615

Falling object 9 0.923

Fire 1 0.103


Well problem 3 0.308

38

Table 27 Production semisubmersibles. UKCS, 1980-92.


Period Year

1980-89 1990 1991 1992


Anchor failure 4 0.222 2 0.5 1 0.293

Blowout

Capsize

Collision

Contact 1 0.056 1 0.333

Crane 10 0.556 5 1.667 1 0.293

Explosion 2 0.111 1 0.25

Falling object 11 0.611 1 0.25 5 1.667 1 0.293

Fire 6 0.333 2 0.5

Foundering

Grounding

Helicopter

Leakage

List

Machinery


Spill/release 6 0.333 1 0.25 1 0.293

Structural 1 0.056

Towing/towline

Well problem

Other 1 0.056

39



Year

1993 1994 1995 1996



Blowout

Capsize

Collision

Contact

Crane 1 0.25 2 0.423 3 0.6 2 0.4

Explosion

Falling object 1 0.25 1 0.214 2 0.4 2 0.4

Fire

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release 2 0.5 3 0.643 2 0.4 1 0.2

Structural

Towing/towline

Well problem

Other

40



Year

1997 1998 1999


Anchor failure

Blowout

Capsize

Collision

Contact 1 0.200

Crane 3 0.6 1 0.200

Explosion

Falling object 4 0.8 1 0.2 1 0.200

Fire 3 0.600

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release 7 1.4 1 0.2 8 1.600

Structural

Towing/towline

Well problem

Other 1 0.2 1 0.200

41

Table 30 Production semisubmersibles. UKCS, 2000-2001, 1990-99, 1980-2001. No. of occurrences and occurrence frequencies (per unit year). Source: ORION

Year Period

2000 2001 1990-99 1980-2001



Blowout

Capsize

Collision

Contact 1 0.200 2 0.045 4 0.055

Crane 1 0.200 5 1.000 18 0.408 34 0.472

Explosion 1 0.023 3 0.042

Falling object 1 0.200 7 1.400 19 0.431 38 0.527

Fire 3 0.600 1 0.200 5 0.113 15 0.208

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release 25 5.000 15 3.000 26 0.590 72 0.999

Structural 1 0.014

Towing/towline

Well problem 1 0.200 1 0.014

Other 1 0.200 3 0.068 5 0.069

42

Table 31 Tension-leg platforms. UKCS, 1980-92.


Period Year

1980-89 1990 1991 1992


Anchor failure

Blowout

Capsize

Collision

Contact 1 0.185

Crane 19 3.506 4 4 9 9 8 8

Explosion

Falling object 15 2.768 3 3 10 10 9 9

Fire 3 0.554 3 3

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release 3 0.554 2 2 1 1

Structural

Towing/towline

Well problem

Other 1 0.185

43



Year

1993 1994 1995 1996


Anchor failure

Blowout 1 1

Capsize

Collision

Contact 1 1

Crane 3 3 4 4 1 1

Explosion 1 1

Falling object 2 2 3 3 5 5 1 1

Fire 2 2 1 1 3 3

Foundering

Grounding

Helicopter 1 1

Leakage

List

Machinery

Off position

Spill/release 1 1 1 1 3 3 1 1

Structural

Towing/towline

Well problem 1 1

Other

44



Year

1997 1998 1999


Anchor failure

Blowout

Capsize

Collision

Contact

Crane 2 2 1 1

Explosion


Fire

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release 1 1

Structural

Towing/towline

Well problem

Other

45

Table 34 Tension-leg platforms. UKCS, 2000-2001, 1990-99, 1980-2001.


Year Period

2000 2001 1990-99 1980-2001


Anchor failure

Blowout 1 0.100 1 0.057

Capsize

Collision

Contact 1 0.100 2 0.115

Crane 32 3.200 51 2.928

Explosion 1 0.100 1 0.057

Falling object 3 3.000 37 3.700 55 3.157

Fire 2 2.000 9 0.900 14 0.804

Foundering

Grounding

Helicopter 1 0.100 1 0.057

Leakage

List

Machinery

Off position

Spill/release 2 2.000 4 4.000 10 1.000 19 1.091

Structural

Towing/towline

Well problem 1 1.000 1 0.100 2 0.115

Other

6.3.4 Monohull Units In the following tables the number of occurrences and corresponding frequencies for monohull units are given per type of unit and year/period. The monohulls comprise both FSUs and FPSOs (both converted tankers and purpose-built units). N denotes number of occurrences and F denotes frequency, i.e. number of occurrences per unit and year. Blank cells denote no occurrences recorded.

46

6.3.4.1 FPSOs Both types

The following tables show the calculated frequencies for FPSOs irrespective of type of construction (i.e. converted or purpose-built)

Table 35 FPSOs. UKCS, 1980-92.


Period Year

1980-89 1990 1991 1992


Anchor failure

Blowout

Capsize

Collision

Contact 1 1

Crane 1 1

Explosion

Falling object 1 1

Fire 1 1

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position


Structural

Towing/towline

Well problem

Other 2 2

47



Year

1993 1994 1995 1996


Anchor failure 1 0.5 3 1.5 1 0.24

Blowout

Capsize

Collision

Contact 2 1

Crane 3 1.5 1 0.5 2 0.62 1 0.24

Explosion 1 0.5 1 0.31

Falling object 3 1.5 2 1.0 3 0.92 1 0.24

Fire 1 0.5 2 1.0 3 0.92 2 0.47

Foundering

Grounding

Helicopter 1 0.5

Leakage

List

Machinery

Off position 1 0.5

Spill/release 3 1.5 14 7 13 4 3 0.71

Structural 1 0.5 1 0.31

Towing/towline

Well problem

Other 2 1 1 0.31

48



Year

1997 1998 1999



Blowout

Capsize

Collision

Contact 1 0.11 2 0.160

Crane 13 1.97 3 0.32 6 0.480

Explosion

Falling object 13 1.97 5 0.53 8 0.640

Fire 4 0.320

Foundering

Grounding

Helicopter

Leakage 1 0.080

List 1 0.080

Machinery

Off position

Spill/release 3 0.46 10 1.05 32 2.560

Structural 1 0.080

Towing/towline

Well problem

Other 1 0.15 8 0.640

49

Table 38 FPSOs. UKCS, 2000-2001, 1990-99, 1980-2001.


Year Period

2000 2001 1990-99 1980-2001



Blowout

Capsize

Collision

Contact 6 0.139 6 0.084

Crane 7 0.538 7 0.528 27 0.627 41 0.577

Explosion 2 0.046 2 0.028

Falling object 11 0.846 7 0.528 33 0.766 51 0.718

Fire 9 0.692 6 0.453 13 0.302 28 0.394

Foundering

Grounding

Helicopter 1 0.023 1 0.014

Leakage 1 0.023 1 0.014

List 1 0.023 1 0.014

Machinery

Off position 2 0.046 1 0.014

Spill/release 49 3.769 23 1.736 82 1.903 154 2.167

Structural 1 0.077 3 0.070 4 0.056

Towing/towline

Well problem 1 0.075 1 0.014

Other 2 0.154 2 0.151 14 0.325 18 0.253

50

In Table 39 below the frequencies for purpose-built and converted FPSOs are shown separately for the period 1980-2001.

Table 39 FPSOs. Type of event vs. type of FPSO. UKCS, 1980-2001.


Type of construction

Purpose-built Converted

Type of event N F N F


Blowout

Capsize

Collision

Contact 6 0.107

Crane 32 0.571 9 0.600

Explosion 2 0.036

Falling object 39 0.695 12 0.800

Fire 21 0.374 7 0.467

Foundering

Grounding

Helicopter 1 0.018

Leakage 1 0.018

List 1 0.018

Machinery


Spill/release 109 1.944 45 3.000

Structural 2 0.036

Towing/towline


Other 15 0.267 3 0.200

51

6.3.4.2 FSUs The tables below show the calculated frequencies for FSUs.

Table 40 FSUs. UKCS, 1980-92.


Period Year

1980-89 1990 1991 1992


Anchor failure 1 1

Blowout

Capsize

Collision

Contact

Crane 2 0.207

Explosion

Falling object 2 0.207 1 1 1 1

Fire 1 0.103

Foundering

Grounding

Helicopter

Leakage

List

Machinery



Structural 1 0.103

Towing/towline

Well problem

Other

52



Year

1993 1994 1995 1996


Anchor failure

Blowout

Capsize

Collision

Contact

Crane 1 0.43

Explosion


Fire

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position


Structural 1 0.33

Towing/towline

Well problem

Other 1 0.33

53



Year

1997 1998 1999


Anchor failure

Blowout

Capsize

Collision

Contact

Crane 1 0.500

Explosion

Falling object

Fire

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release

Structural

Towing/towline

Well problem

Other

54

Table 43 FSUs. UKCS, 2000-2001, 1990-99, 1980-2001.


Year Period

2000 2001 1990-99 1980-2001



Blowout

Capsize

Collision

Contact 1 0.481 1 3.333 2 0.057

Crane 1 0.481 1 3.333 2 0.092 6 0.172

Explosion

Falling object 1 0.481 1 3.333 3 0.137 7 0.201

Fire 1 0.029

Foundering

Grounding

Helicopter

Leakage

List

Machinery


Spill/release 1 3.333 2 0.092 4 0.115

Structural 1 0.137 2 0.057

Towing/towline

Well problem

Other 1 0.137 1 0.029

55

6.3.5 Accommodation Units Since no exposure data for these type of units are available, only the number of occurrences are given (i.e. no frequencies). These units comprise both the jackup and semisubmersible types.

Table 44 Accommodation units. UKCS, 1980-92. No. of occurrences. Source: ORION

Period Year

1980-89 1990 1991 1992

Type of event Jackup Semisub. Jackup Semisub. Jackup Semisub. Jackup Semisub.

Anchor failure 1 1 4

Blowout

Capsize

Collision

Contact 1

Crane 2 3 6

Explosion

Falling object 5 5 6

Fire 1 2

Foundering

Grounding

Helicopter 1

Leakage

List

Machinery

Off position 2 1 1

Spill/release

Structural 2 2

Towing/towline

Well problem

Other 1

56


Year

1993 1994 1995 1996


Anchor failure 6 5 1 2

Blowout

Capsize

Collision

Contact 1

Crane 4 1 1 3

Explosion


Fire 1 3 1

Foundering

Grounding

Helicopter

Leakage

List

Machinery 1

Off position 4

Spill/release 1

Structural 1

Towing/towline 1

Well problem

Other

57


Year

1997 1998 1999

Type of event Jackup Semisub. Jackup Semisub. Jackup Semisub.

Anchor failure 1

Blowout

Capsize

Collision

Contact 1

Crane 2

Explosion

Falling object 2

Fire 1

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position

Spill/release

Structural

Towing/towline

Well problem

Other

58

Table 47 Accommodation units. UKCS, 2000-2001, 1990-99, 1980-2001. No. of occurrences. Source: ORION

Year Period

2000 2001 1990-99 1980-2001


Anchor failure 1 2 19 2 23

Blowout

Capsize

Collision

Contact 1 2 3 5

Crane 4 18 6 24

Explosion 1


Fire 9 10

Foundering

Grounding

Helicopter 1 3

Leakage

List

Machinery 1 1

Off position 8 10

Spill/release 1 1

Structural 1 4 2 5

Towing/towline 1 1

Well problem

Other 1 1

59

7 FOCUS/SHIELD DATABASE The Health and Safety Executive – Field Operations Division (HSE-FOD) records all received RIDDOR forms in a database called FOCUS.

FOCUS has been in existence since April 1996, prior to this date the database was known as SHIELD. Very little of the data recorded in SHIELD has been transferred to FOCUS, and, due to rigid interpretation of the Data Protection Act, it is unlikely that SHIELD will be retained. Databases can only be maintained if they are “live”. However, the decision has not been made as yet and SHIELD may be retained on a CD-ROM. It may still be interrogated.

FOCUS itself is a Windows operated comprehensive database. HSE-FOD is divided into 20 UK areas and each has its own local database. Each local database is uploaded on a daily basis to the national FOCUS database. The administration of the database was found to be efficient.

Anyone with access to a FOCUS terminal anywhere in the UK can interrogate the database on a Read-Only basis using comprehensive search tools. Coding lists are available both from the screen and in a separate manual.

Essentially, being onshore based, FOCUS attaches each incident or accident to what is called an “Incumbent”, which is defined as a combination of Client and Site.

The screen for the basic details of an incident includes date, location, time and name of the main Company contact and the sub contractors address, if applicable.

If an incident occurs on an offshore mobile installation that is alongside in a yard in the UK, then the ‘location’ is coded as the name of the installation and the ‘sub contractor’ is coded as the name and address of the owner of the installation.

As a consequence of the above it is possible to search for incidents on offshore vessels in the database using a list of major operators of such vessels.

All information including investigations, prosecutions, inspections, etc. is included in FOCUS, but all information has to be recorded by hand, no documents can be attached to the system.

7.1 Result of interrogation The interrogation of the FOCUS database resulted in only 1 accident. This event is also recorded in WOAD. No further evaluation has been done.

61

8 THE MAIB DATABASE The Marine Accident Investigation Branch (MAIB) is a distinct and separate branch within the Department of the Environment, Transport and the Regions (DETR). Its Chief Inspector reports directly to the Secretary of State for the Environment, Transport and the Regions on marine accident investigations. The authority of the MAIB to investigate marine accidents originates from the Merchant Shipping Act 1995. MAIB’s responsibility covers the investigation of accidents to or on:

½ all UK registered vessels anywhere in the world ½ other vessels being within the 12-mile zone of the UK coast (UK territorial waters)

For offshore floating vessels all accidents and incidents occurring in transit should be reported to MAIB according to the above.

Accidents must be reported as soon as possible to the MAIB by the quickest means available. Serious injuries and dangerous occurrences must be reported within 14 days or within 14 days after arrival at the next port if the vessel is at sea at time of the accident. The reporting form presently being used is IRF (1/98).

About 2000 accidents are reported per year to MAIB of which about 500 require some sort of MAIB correspondence follow-up, for clarification purposes or investigation. Most of these are from UK waters. Additional information about reporting and investigations of accidents by the MAIB is found in Memorandum on the Investigations of Marine Accidents; MAIB/DETR. January 1998.

MAIB maintains a database covering accidents and incidents from 1991 to date. The received forms and notifications are recorded in the database by a staff of two persons. Beside the said forms and notifications, the ‘Coast Guard Morning Reports’ serves as first-hand information input to the database. Today the database contains some 18.000 events covering all types of incidents and accidents, ranging from smaller low-consequence events and near-misses to major accidents with loss of life.

8.1 Available data and reporting For the purposes of this project MAIB made available information from their database on an Excel spreadsheet covering the years 1990-2001 (only 1 event in 1990). MAIB were set up in 1989. The database records date from 1991. Records prior to that date and back to 1984 are held in log books (available at MAIB). However, this material has not been utilised in this project.

It has been realised that MAIB receives very few reports of incidents involving offshore units and especially incidents occurring outside UK 12 mile territorial waters. MAIB have no independent criteria for what is to be defined as the ”transit" phase of a unit. If a major incident occurs involving an offshore unit and there are any complications regarding the jurisdiction MAIB will contact HSE and discuss the incident.

If a minor incident occurs and it is not absolutely clear whether the vessel was in transit MAIB tend to take the view that the incident would not have been reported to MAIB unless, in the opinion of the operators, the vessel was in transit.

63

The MAIB’s regulations apply to any United Kingdom ship and any other ship within the United Kingdom or the territorial waters thereof. However there is no requirement for foreign ships within UK 12 mile territorial waters to report incidents to MAIB unless they are within the limits of a port or are carrying passengers to or from a port in the United Kingdom. I.e., MAIB may investigate accidents that occur in territorial waters, but there is no requirement for reporting such events to the MAIB.

8.2 Result of interrogation The search in the database for incidents on mobile installations in transit inside the UK border resulted in 58 relevant events. The following two tables summarises the results of the search. Blank cells denote no accidents/occurrences recorded.

Table 48 Floating units. UKCS, 1990-2001. No. of accidents. Source: MAIB

Number of accidents



1990 1 1

1991 12 1 13

1992 9 9

1993 7 1 8

1994 1 1

1995 2 1 3

1996 6 1 7

1997 1 1 2

1998 3 3

1999 3 1 4

2000 1 2 1 4

2001 1 1 1 3

Total 47 4 6 1 58

64

Table 49 Floating units. UKCS, 1990-2001. No. of occurrences. Source: MAIB




Anchor failure 4 1 5

Blowout -

Capsize 1 1

Collision 6 1 7

Contact 23 3 1 29

Crane 4 1 1 6

Explosion 1 1


Fire 4 4

Foundering 1 1

Grounding 1 1

Helicopter

Leakage 2 1 2

List 1 1

Machinery 2 2

Off position 1 1

Spill/release 1 1

Structural 3 3

Towing/towline

Well problem 1

Other 1 1

Since the MAIB largely covers the floating units in transit and limited to the period after 1990, it was decided not to calculate separate frequencies based on these accident data. This is because it is not possible to explicitly obtain exposure data for the transit/transfer phase.

65

9 WOAD One of the main sources for offshore accident information for public use is the Worldwide Offshore Accident Databank (WOAD) operated by Det Norske Veritas (DNV). WOAD contains some 4.300 events from the period 1970-2001, derived mainly from public-domain sources such as Lloyds Casualty Reports, newspapers and official publications. Most of the data is from the UK and Norwegian Sectors and the US Gulf of Mexico. Exposure data is also provided, allowing accident rates to be calculated for different accident types, unit types, geographical locations, degrees of damage, etc. Accident frequencies obtained from WOAD are summarised in the WOAD Statistical Report (ref. /2/).

9.1 Available data The WOAD database contains information on accidents for floating units on the UKCS since 1970. Each record in the database contains information on a number of aspects concerning the installation and the accident. Below is given a sample record from the database with a selection of parameters, only.

Date 891108

Time 1800

Type Jackup

Name

Operation mode Mobilise to drill

Chain of events Towline failure-Drift off-Capsize-Sinking

No. of injuries 0

No. of fatalities 0

Degree of damage Total loss

No. of evacuees 51

Description While mobilising under assistance of two tugs, one of the two towlines parted caused by heavy seas and the rig became adrift. A combination of electric power failing and the rig taking on water caused the jackup to capsize subsequent sinking in 100-ft waters. The rig was later declared a constructive total loss. The 51-member crew was safely evacuated by helicopter.

67

9.2 Result of interrogation The database was interrogated for retrieval of relevant records and the search resulted in 157 records matching the defined search criterion (period: 1980-2001, type of unit: MODU, MOPU, Monohull, geographical area: North Sea, UK shelf).

The following two tables summarises the results of the search. Blank cells denote no accidents/occurrences recorded.

Table 50 Floating units. UKCS, 1980-2001. No. of accidents. Source: WOAD

Number of accidents



1980-89 48 7 2 57

1990 15 1 3 19

1991 13 13

1992 6 1 1 8

1993 8 1 9

1994 4 2 1 2 9

1995 9 9

1996 9 9

1997 1 2 3

1998 2 3 5

1999 2 2 4

2000 8 1 1 10

2001 2 2

1990-99 69 5 5 9 88

1980-2001 127 12 8 10 157

68

Table 51 Floating units. UKCS, 1980-2001. No. of occurrences. Source: WOAD




Anchor failure 21 4 3 1 29

Blowout 5 5

Capsize 2 2

Collision 9 1 10

Contact 13 1 2 2 18

Crane 8 1 9

Explosion 4 4

Falling object 14 1 15

Fire 7 2 1 10

Foundering 1 1

Grounding 3 1 4

Helicopter 3 3

Leakage 3 3

List 3 3

Machinery

Off position 23 1 1 25


Structural 12 3 1 2 18

Towing/towline 18 18

Well problem 19 1 20

Other 12 2 3 17

The results from performing a statistical analysis of the data are shown in the following sections.

When giving accident frequencies per type of event, this is presented as number of occurrences per unit per year (ref. sections 9.2.2-9.2.4).

However, when presenting frequencies irrespective of type of event, the figures are given as number of accidents per unit per year (ref. section 9.2.1).

69

9.2.1 All floating units The table below shows the accident frequencies (i.e. number of accidents per unit-year) for all floating units on the UKCS in 1980-2001, except for the accommodation units for which no exposure data is obtained.

Table 52 Floating units. UKCS, 1980-2001. Accident frequencies. Source: WOAD

Year of event

Mobile Drilling Units

Mobile Production

Units

Monohull Units Total*

1980-89 0.087 0.299 0.094

1990 0.202 0.2 0.197

1991 0.164 0.152

1992 0.077 0.226 0.083

1993 0.112 0.2 0.112

1994 0.069 0.352 0.369 0.116

1995 0.162 0.133

1996 0.146 0.12

1997 0.017 0.214 0.041

1998 0.034 0.261 0.066

1999 0.035 0.138 0.050

2000 0.151 0.066 0.118

2001 0.037 0.026

1990-99 0.106 0.084 0.139 0.107

1980-2001 0.097 0.120 0.094 0.098

*) Excl. accommodation units

70

9.2.2 Mobile Drilling Units (MODUs) In the following tables the number of occurrences and corresponding frequencies are given per type of MODU and year/period. N denotes number of occurrences and F denotes frequency, i.e. number of occurrences per unit and year. Blank cells denote no occurrences recorded (and hence no frequencies calculated).

9.2.2.1 Drilling jackups and semisubmersibles


No. of occurrences and occurrence frequencies (per unit year). Source: WOAD

Period Year

1980-89 1990 1991 1992


Anchor failure

Blowout

Capsize

Collision 2 9.7•10-3

Contact 2 9.7•10-3 1 0.036 1 0.034

Crane 2 9.7•10-3

Explosion

Falling object

Fire


Grounding

Helicopter

Leakage 1 0.036

List 1 0.036

Machinery

Off position 4 0.019 1 0.034

Spill/release 1 4.9•10-3

Structural 3 0.015



Other 2 9.7•10-3

71



Year

1993 1994 1995 1996


Anchor failure

Blowout

Capsize

Collision 1 0.038

Contact 2 0.092

Crane 1 0.048

Explosion


Fire

Foundering

Grounding

Helicopter

Leakage

List 1 0.048

Machinery



Structural 2 0.075 1 0.048

Towing/towline

Well problem 1 0.046 1 0.043

Other 1 0.043

72



Year

1997 1998 1999


Anchor failure

Blowout

Capsize

Collision

Contact

Crane

Explosion

Falling object

Fire

Foundering

Grounding

Helicopter

Leakage

List

Machinery


Spill/release

Structural 1 0.042

Towing/towline

Well problem

Other

73

Table 56 Drilling jackups. UKCS, 2000-2001, 1990-99. 1980-2001.


Year Period

2000 2001 1990-99 1980-2001


Anchor failure

Blowout 1 0.045 1 2.0•10-3

Capsize 2 4.0•10-3

Collision 1 4.1•10-3 3 6.0•10-3

Contact 4 0.016 6 0.012

Crane 1 0.045 1 4.1•10-3 2 4.0•10-3

Explosion

Falling object 1 0.045 1 4.1•10-3 2 4.0•10-3

Fire 1 2.0•10-3


Grounding

Helicopter

Leakage 1 4.1•10-3 1 2.0•10-3

List 2 8.1•10-3 2 4.0•10-3

Machinery

Off position 3 0.012 7 0.014

Spill/release 2 8.1•10-3 3 6.0•10-3

Structural 2 0.089 4 0.016 9 0.018

Towing/towline 1 4.1•10-3 5 0.010

Well problem 1 0.045 2 8.1•10-3 7 0.014

Other 1 4.1•10-3 3 6.0•10-3

74



Period Year

1980-89 1990 1991 1992


Anchor failure 4 0.012 4 0.087 2 0.041 4 0.083

Blowout 2 5.9•10-3 1 0.022 1 0.02

Capsize

Collision 2 5.9•10-3 1 0.022

Contact 4 0.012 2 0.041

Crane 2 0.043

Explosion 3 8.9•10-3

Falling object 1 2.9•10-3 2 0.043 1 0.02

Fire 4 0.012

Foundering



Leakage 1 0.022 1 0.02

List 1 2.9•10-3

Machinery

Off position 6 0.018 1 0.022 3 0.061

Spill/release 5 0.015 1 0.022 1 0.02

Structural 2 5.9•10-3 1 0.02

Towing/towline 6 0.018 1 0.022 2 0.041

Well problem 5 0.015 2 0.043 3 0.061

Other 3 8.9•10-3 1 0.022 3 0.061 1 0.021

75



Year

1993 1994 1995 1996



Blowout

Capsize

Collision 2 0.058 1 0.026

Contact

Crane 1 0.023 1 0.029 1 0.026

Explosion

Falling object 1 0.023 2 0.058 1 0.026

Fire 1 0.029

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position 1 0.023 1 0.028 2 0.052


Structural



Other 1 0.023

76



Year

1997 1998 1999



Blowout

Capsize

Collision

Contact 1 0.028

Crane

Explosion 1 0.027


Fire 1 0.027

Foundering

Grounding

Helicopter

Leakage

List

Machinery



Structural

Towing/towline

Well problem

Other

77

Table 60 Drilling semisubmersibles. UKCS, 2000-2001, 1980-2001.


Year Period

2000 2001 1990-99 1980-2001


Anchor failure 1 0.033 16 0.040 21 0.026

Blowout 2 5.0•10-3 4 5.0•10-3

Capsize

Collision 4 0.010 6 7.5•10-3

Contact 3 7.5•10-3 7 8.7•10-3

Crane 1 0.033 5 0.012 6 7.5•10-3

Explosion 1 2.5•10-3 4 5.0•10-3

Falling object 3 0.099 1 0.033 8 0.020 13 0.016

Fire 2 5.0•10-3 6 7.5•10-3

Foundering

Grounding 1 2.5•10-3 3 3.7•10-3


Leakage 2 5.0•10-3 2 2.5•10-3

List 1 1.2•10-3

Machinery

Off position 1 0.033 9 0.022 16 0.020


Structural 1 2.5•10-3 3 3.7•10-3


Well problem 7 0.017 12 0.015

Other 5 0.012 8 0.010

9.2.2.2 Drill ships WOAD has only recorded 2 accidents on drillships in the period 1980-2001. Combined with the corresponding exposure of 7.6 years, the accident frequency becomes 0.26 accidents per year.

78

9.2.3 Mobile Production Units (MOPUs) In the following tables the number of occurrences and corresponding frequencies are given per type of MOPU and year/period. N denotes number of occurrences and F denotes frequency, i.e. number of occurrences per unit and year. Blank cells denote no occurrences recorded (and hence no frequencies calculated). Note that no accidents to production jackups are recorded in WOAD.

9.2.3.1 Production semisubmersibles



Period

1980-89 1990-99 1980-2001


Anchor failure 1 0.056 3 0.068 4 0.055

Blowout

Capsize

Collision

Contact 1 1 0.014

Crane

Explosion

Falling object

Fire 2 0.11 2 0.028

Foundering

Grounding

Helicopter

Leakage

List

Machinery

Off position 1 1 0.014

Spill/release 1 1 0.023 2 0.028

Structural 2 0.11 2 0.028

Towing/towline

Well problem

Other

79

9.2.3.2 Production jackups No accidents are recorded on production jackups in the

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